There is still debate about whether Lowland Anoa (Bubalus depressicornis) and Mountain Anoa (Bubalus quarlesi) are distinct species (Burton et al. 2005). Two phenotypes of anoa, characterized by body size, hair texture, horn shape, and presumably body colours have been used by certain authors to justify the existence of two species. However, transitory morphs suggest that the real relationships are more complex, and hardly understood. Sulawesi is a rather small territory, so the speciation patterns of a large mammal pose a riddle to systematists. An enormous underlying variability (outward appearance, anatomy, chromosomes, proteins, DNA) has hitherto precluded a convincing classification, or has questioned the validity of an approach to group anoa diversity into clear, reproducible types. Pattern-based classifications of zoo and museum specimens, most of which are devoid of reliable information as to their origin within Sulawesi, have always suffered from the later discovery of phenotypes with new combinations of supposedly diagnostic species characters.

The "transitory populations" probably do not represent "hybrids" of two species, but various degrees of genetic introgression, or even primary clines of diverging evolutionary lineages, and they could perhaps differ in different regions of Sulawesi, depending on the degree of gene flow, and the characters affected. At the present stage of insight, every regional anoa population should be considered worthy of conservation. The management units should at least be based on known origins from within Sulawesi, rather than on taxonomic schemes, which in the past have often proved incomplete.

The English common names of the two species relate to a still uncertain altitudinal separation (Groves 1969), with the large form (Lowland Anoa) inhabiting low-lying areas and the smaller form (Mountain Anoa) living at higher elevations (Burton et al. 2005).

Justification:
This species is considered Endangered because its population is estimated to be less than 2,500 mature individuals, its rate of decline is believed to be greater than 20% over two generations (14 to 18 years), and no subpopulation is believed to number more than 250 mature individuals.

This species is endemic to Indonesia, where it is found only on Sulawesi and Buton Island off the southeast coast, with no records of either species of Anoas from other small neighbouring islands adjacent to Sulawesi (Burton et al. 2005). This species has been typically recorded from 1,000 to 2,300 m, but can be found at near sea level (National Research Council 1983, Sugiharta 1994, G. Semiadi pers. comm. 2006). It remains uncertain whether the two putative species, Bubalus depressicornis and Bubalus quarlesi, are sympatric or parapatric in their distribution (Burton et al. 2005). Across the island, local distribution of anoa species remains unclear, as they may occur in forest patches at different altitudes or sympatrically (Burton et al. 2005). Records of skulls and morphological descriptions of this species recently could only confirm that it was present across most of the Central region of Sulawesi and in the north of Buton Island (Burton et al. 2005). However, slightly earlier reports suggest the Mountain Anoa also occurs in the north peninsular and part way along the southeastern peninsular (Groves 1969). Both of these areas still sustain anoa populations, so these may include populations of Mountain Anoa. Identifying Mountain Anoa, and therefore their range, is made difficult by the fact that they cannot be differentiated from young Lowland Anoa. Historically, anoas of one species or other were present throughout the majority of the island’s forests (Weber 1890, Sarasin and Sarasin 1901, Mohr 1921, Harper 1945, Groves 1969, Burton et al. 2005).

Too few data exist to precisely quantify the current abundance of Mountain Anoa. Nevertheless, they still appear to be distributed relatively widely within their known historical range on Sulawesi. However, there is little doubt that they have been in decline (i.e., there has been a decrease in their range and abundance) since the end of the 19th century. They have declined over the 1980 to 2000 period (ca. three generations), precipitously in some areas. The population size is unknown because there have been no island-wide surveys to estimate this, even for the largest populations. Estimating the population size is further complicated by the uncertain distribution of the two anoa species. It is thought that there are less than 2,500 mature individuals. There have been declines of this species throughout Sulawesi, especially in the southern and northeastern peninsulas, with the decline attributed to hunting for meat and habitat loss (Burton et al. 2005). Most populations are becoming rapidly fragmented, suggesting that conservation of viable populations may soon require management of metapopulations (Burton et al. 2005). It is thought no subpopulation exceeds 250 mature individuals. The current status of the species is consequently a matter for concern because even the subpopulations in large protected areas (e.g., Lore Lindu National Park) and other large forest blocks are reported to be in decline as a result of heavy hunting pressure. There are two areas where the declines have been most serious, Gorontalo and Buol Toli-Toli (G. Semiadi pers. comm. 2006). Overall, the decline rate is not well known, however, based on distribution surveys and questionnaires, the range of this species is retreating to the central parts of forested areas. The rate of population decline across their range is thought to be 20% over two generations (generation length of 7 to 9 years).

There is very little is known about the ecology and life history of the Anoas (Burton et al. 2005). This species is typically found in dense forest as opposed to more open subalpine habitats, and prefers habitats with dense understory vegetation (Foead 1992, Sugiharta 1994, G. Semiadi pers. comm. 2006). Mountain Anoas typically live near abundant water sources in areas with low human activity (Sugiharta 1994), and in the past there are records at sea level. Like other wild buffalo, Anoas wallow and bathe in pools of water and/or mud. It is probable that mineral springs or licks are also required, although Anoa are reported to drink seawater, which might fulfil their mineral needs in areas without licks or springs. The species is solitary and is a browser, feeding on grasses and other vegetation (Whitten et al. 1987, Foead 1992). The typical life span in captivity is reported to be 20 to 30 years, with age at sexual maturity at 2 to 3 years old (in captivity), with typically one offspring per year (NRC 1983, Jahja 1987), though in wild conditions this may be less.

The two major threats to this species are hunting, for food, and habitat degradation (Burton et al. 2005) due to agriculture, mining (gold mining) (G. Semiadi and D. Gunaryadi pers. comm. 2006). Illegal international trade in live animals or body parts is not thought to present a serious threat.

This species is listed in CITES under Appendix I, and fully protected under Indonesian law (Jahja 1987, Burton et al. 2005). Mountain Anoa occur in a number of protected areas. There are several key protected areas thought to hold significant populations of this species, including Lore Lindu National Park, Bogani Nani-Wartabone National Park, and Tanjung Peropa Nature Reserve on Sulawesi (Burton et al. 2005). There is an on-going status survey, as well as genetic and morphological research that aims to clarify the confusion that surrounds anoa systematics. A small number of Mountain Anoa are in captivity, but the breeding program has been greatly hindered by the difficulties of assigning captive anoa to appropriate taxa. The captive population has around five individuals in a Mountain Anoa breed line (J. Burton pers. comm.), although the taxonomic status of most individuals remains uncertain (Nötzold 1999).

According to Burton et al. (2005) this species requires the following conservation actions: (1) protection from hunting, (2) prevention of habitat loss at key sites, (3) complete genetic studies to better determine the taxonomy of this species, and (4) determination of the status of remaining populations. Law enforcement combined with education should be employed to reduce hunting pressure.

Burton, J. A. 2001. The Anoa 2000 Conservation Project. Field Report: Systematics and Conservation of Large Mammals in South East Sulawesi (Sulawesi Tenggara), with Notes on North and Central Sulawesi. Unpublished Report.